Masking plug



FIG. 1 is a perspective view of a masking plug embodying the invention.

FIG. 2 is a top view of the masking plug of FIG. 1.

FIG. 3 is a side view of the masking plug of FIG. 1; and,

FIG. 4 is a bottom view of the masking plug of FIG. 1. 

CLAIM We claim the ornamental design for a masking plug, as shown and described. 